On the day Metro blamed the major delays on a ‘signalling issue’, however industry insiders told the Herald Sun a potentially life-threatening incident was the real cause.

Metro and the national rail watchdog are looking into how the early morning train almost struck a maintenance truck, with the train slamming on the brakes and pulling up just short of what would have been a serious accident.

Metro and the national rail watchdog are looking into how an early morning train almost struck a maintenance truck. Picture: Nicole GarmstonMetro spokeswoman Sammie Black confirmed the near miss and said an investigation had been launched.

“We are absolutely committed to running a safe rail network and have launched an investigation immediately to understand all the factors involved. This investigation is ongoing,” Ms Black said.

“Trains were stopped while we ensured we had eliminated any safety risk and apologise to our passengers for the delays this caused, which we know were frustrating.”

It is understood the incident occurred about 10.15am when Metro claim a maintenance vehicle was reported to be out of position on the tracks between Flinders St and Richmond stations.

An approaching train slowed and stopped more than 60m from the maintenance vehicle without the use of emergency brakes, and was able to be moved to a platform at Flinders St for passengers to disembark.

The incident triggered a signalling response to bring all trains in the vicinity safely to a stop.

The Office of the National Rail Safety Regulator is investigating the incident, which a union official labelled as a “concerning breakdown in communication”.

Racing fans headed to Flemington for last Saturday’s Turnbull Stakes were forced to get off the train at Flinders St Station, with delays also felt on the Lilydale/Belgrave and Alamein lines.